Retinoid-related orphan receptors (ROR) are reported to have an important role in numerous biological processes. See, for example, Dussault et al. in Mech. Dev. (1998) vol. 70, 147-153; and Andre et al. in EMBO J. (1998) vol. 17, 3867-3877. Scientific investigations relating to each of retinoid-related orphan receptors RORα, RORβ, and RORγ have been described in the literature. See, for example, Hirose et al. in Biochem. Biophys. Res. Commun. (1994) vol. 205, 1976-1983; Giguere et al. in Genes. Dev. (1994) vol. 8, 538-553; Medvedev et al. in Gene (1996) vol. 181, 199-206; Ortiz et al. in Mol. Endocrinol. (1995) vol. 9, 1679-1691; and A. M. Jetten in Curr Drug Targets Inflamm Allergy (2004) vol. 3, 395-412). Continuing research in this field is spurred by the promise of developing new therapeutic agents to treat medical disorders associated with retinoid-related orphan receptor activity.
RORγ has been reported to be expressed in high concentration in various tissues, such as thymus, kidney, liver, muscle, and certain fat tissue. See, for example, Hirose et al. in Biochem. Biophys. Res. Commun. (1994) vol. 205, 1976-1983; Medvedev et al. in Gene (1996) vol. 181, 199-206; Ortiz et al. in Mol. Endocrinol. (1995) vol. 9, 1679-1691; and He et al. in Immunity (1998) vol. 9, 797-806. Two isoforms of RORγ have been identified and are referred to as γ1 and γ2 (also referred to as RORγt). See, for example, He et al. in Immunity (1998) vol. 9, 797-806. Expression of the γ2 isoform has been reported to appear in, for example, double-positive thymocytes. See, for example, He et al. in Immunity (1998) vol. 9, 797-806; and Villey et al. in Eur. J. Immunol. (1999) vol. 29, 4072-4080. RORγt plays a critical role in regulating differentiation of Th17 cells, a subset of T helper lymphocytes. See, for example, Ivanov et al. in Cell (2006) vol. 126, 1121-1133. Th17 cells are important for recruiting tumor-killing cytotoxic CD8+ T cells and natural killer cells into the tumor microenvironment. The level of Th17 cells correlated positively with patient survival or slower disease progression in certain cancers. See, for example, Kryczek et al. in Blood (2009) vol 114, 1141-1149; and Sfanos et al. in Clinical Cancer Research (2008) vol 14, 3254-3261. Compounds capable of enhancing RORγt activity are thus contemplated to provide a therapeutic benefit in the treatment of cancer.
Cancer continues to be a significant health problem despite the substantial research efforts and scientific advances reported in the literature for treating this disease. Some of the most frequently diagnosed cancers include prostate cancer, breast cancer, and lung cancer. Prostate cancer is the most common form of cancer in men. Breast cancer remains a leading cause of death in women. Current treatment options for these cancers are not effective for all patients and/or can have substantial adverse side effects.
Accordingly, a need exists for improved treatments for cancer. The present invention addresses this need and provides other related advantages.